At present, liquid crystal displays (LCDs) have become mainstream products in flat display devices due to their characteristics, such as small volume, low power consumption and no radiation. A display panel is a main component in a liquid crystal display device and generally comprises an array substrate and a color filter substrate which are assembled to form a cell.
In the liquid crystal display, in order to obtain a more uniform brightness and a high contrast, the liquid crystal molecules in the display panel are required to maintain specific orientation when no electric field is applied, thus it is necessary to form alignment films (P1) on surfaces of the array substrate and the color filter substrate to be aligned which face each other. The alignment films are usually transferred onto the array substrate and the color filter substrate through a transfer print by an alignment film printing machine. In order to ensure the quality of alignment film printing and quality of the alignment film itself, generally, before the alignment film is printed, it is required to clean the array substrate and the color filter substrate, only by cleaning the incoming substrates (for example, the array substrate and the color filter substrate), perfect print quality and effect of the printed alignment films can be ensured.
Current cleaning of incoming substrate is mainly performed by using lotion and supplying water through a pipe, which has been used for a long time, the pipe is likely left with foreign bodies and impurities (such as scale, lotion particles and other dirt in water) on the inner wall thereof, and thus blocks consisting of the foreign bodied and the impurities may be formed on the inner wall of the pipe, which seriously affects normal supply of water, therefore, normal clean of the incoming substrate may be affected. However, at present, there is no better measure to remove the foreign bodies and impurities inside the pipe.